QT300_03 QUANTUM [Quantum Research Group], QT300_03 Datasheet

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QT300_03

Manufacturer Part Number
QT300_03
Description
CAPACITANCE TO DIGITAL CONVERTER
Manufacturer
QUANTUM [Quantum Research Group]
Datasheet
LQ
The QT300 charge-transfer (“QT’”) IC is a self-contained Capacitance-to-
Digital-Converter (CDC) capable of detecting femotofarad level changes in
capacitance. While designed primarily for instrumentation applications, it can be used
also for touch control applications where signal processing is best handled by a host
MCU.
Primary applications include fluid level sensors, distance sensors, transducer
‘amplifiers’ for pressure and humidity sensing functions, material detectors, and other
uses requiring quantified capacitance data.
Unlike other Quantum products, the QT300 does not process its acquired data. Its only result is raw, unprocessed binary
data which can be transmitted to a host via either a bidirectional SPI interface or a simple polled single wire UART type
interface. This allows the designer to treat the device as a capacitance-to-digital-converter (CDC) for measurement
applications. It is ideal for situations where there are unique signal processing requirements.
The device requires only a single sampling capacitor to function. The value of this capacitor controls the gain of the sensor,
and it can be adjusted over 2½ decades of range from 1nF to 500nF. No external switches, opamps, or other components
are required.
The device operates on demand, and can be synchronized to allow several QT300’s to operate near each other without
cross-interference.
LQ
Capacitance to Digital Converter (CDC) IC
Direct-to-digital conversion, 16 bits
Log response: Wide dynamic range
Outputs raw data to a host device
Single wire UART interface
Master or Slave mode SPI interface
Programmable clock speed
Turns objects into intrinsic touch sensors
One external sample capacitor to control gain
Multiple QT300’s possible on one SPI bus
-40
0
0
C to +70
0
C to +85
T
A
0
C
0
C
Copyright © 2002 QRG Ltd
AVAILABLE OPTIONS
C
APACITANCE TO
QT300-IS
SOIC
-
DRDY
SNS1
SCK
Vss
8-PIN DIP
QT300-D
-
D
1
2
3
4
APPLICATIONS
IGITAL
Fluid level sensors
Prox sensors
Moisture detection
Position sensing
Transducer driver
Material sensors
QT300 R1.01 21/09/03
8
7
6
5
C
QT300
ONVERTER
Vdd
SDO
REQ / 1W
SNS2

Related parts for QT300_03

QT300_03 Summary of contents

Page 1

LQ Capacitance to Digital Converter (CDC) IC Direct-to-digital conversion, 16 bits Log response: Wide dynamic range Outputs raw data to a host device Single wire UART interface Master or Slave mode SPI interface Programmable clock speed Turns objects into intrinsic ...

Page 2

Table 1-1 SPI Mode Pin Description Pin Name 1 /DRDY 2 SCK 3 SNS1 4 VSS Negative supply (ground) 5 SNS2 6 /REQ 7 SDO 8 VDD Table 1-2 1W UART Mode Pin Description Pin Name 1 - Connect to ...

Page 3

The length of this burst is an important parameter directly related to the signal value. The burst duration also affects the response time of the sensor; the larger Cs is, the longer the burst, the slower the ...

Page 4

Figure 3-1 Multiple QT300's on the same SPI port DRDY Host Micro SCK SDI SDO - Serial Data Output; Output-only. This is the data output to the host during an SPI transfer. When not in use, this pin floats. This ...

Page 5

Figure 4-1 UART and Trigger Pulse Signal. back to the host. During idle times this pin floats and therefore must be connected to a pullup resistor. The DRDY line can be used as a Slave Select line (SS). The host ...

Page 6

Trigger pulse description The part wakes from low power mode when the first negative edge is detected on the 1W pin (Figure 4-1, bottom). The negative pulse must be at least 30µs wide. The host then generates the positive ...

Page 7

Electrical specifications 7.1 ABSOLUTE MAXIMUM SPECIFICATIONS Operating temp ...

Page 8

DRDY {from QT300} SCK {from host} SDO {from QT300} DRDY {from QT300} SCK {from QT300} SDO {from QT300} Symbol Parameter T Clock Duration SKD T SCK High Duration SKH T SCK Low Duration SKL SCK High To SDO Ready T ...

Page 9

UART Twu Tbr Tsb Symbol Twu Tbr Baud set pulse Tsb Baud end level Baud rate range Baud rate match accuracy Tacq Acquisition time Tstart Tstop Tmls MSB-LSB spacing MSB LSB Description Symbol Mode SM SCD Clock Speed MSB-LSB ...

Page 10

Cs 400 9nF 19nF 43nF 300 74nF 124nF 200 200nF 100 Load Figure 7-4 Typical resolution vs Cx & Cs; Vdd = 3.0 Volts 5.00% 4.00% 3.00% 2.00% 1.00% 0.00% -1.00% -2.00% -3.00% -4.00% -5.00% ...

Page 11

M Pin SYMBOL Min a 6.1 A 7.62 M 9.02 m 7.62 Q 0.69 L 0.356 L1 1.14 L2 0.203 F 2.54 r 0. Pin 1 F SYMBOL Min a 5.21 ...

Page 12

Tel: +44 (0)23 8056 5600 Fax: +44 (0)23 8045 3939 The specifications set out in this document are subject to change without notice. All products sold and services supplied by QRG are subject to our Terms and Conditions of ...

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